HOW TO USE THE BOOK 



One recognizes a plant by the presence of structural features 

 peculiar to itself, and not found on any other kind of plant. In such 

 a book as this, these characters are given one or a few at a time, 

 and contrasted with the characters which other sorts of plants possess. 

 Such a presentation is called a Key, and by. its proper use the name 

 may be learned of any plant considered in it. This process is called 

 Identification. 



Keys are constructed in several different ways, although the prin- 

 ciple of all is the same. In this book, the user will begin with lines 

 la and Ib on the page headed Key to the Groups. Each of these lines 

 includes some descriptive matter, but only one of them can apply to 

 the plant being identified. For example, if the plant to be identified 

 is an Oak, line la will apply perfectly, and the same line will also 

 apply to any other kind of tree or to any shrub. But if the plant is a 

 Violet, a Buttercup, or any other herb, line Ib agrees and line la 

 will not apply. At the end of each line is a reference to be consulted 

 next. If the plant is a tree or shrub, one turns accordingly to Group 

 1, on page ix, and begins again at the first number given. If the plant 

 is an herb, he follows the reference to line 2, just below, and again 

 compares the plants with lines 2a and 2b. 



Under every number at least two lines of description are given, 

 designated a and b, and under a few numbers additional lines appear, 

 designated c, d, etc. In every case, the user of the key will select 

 from the different lines under the same number that particular line 

 which agrees with the structure of the plant, and follow up the ref- 

 erence given at the end of that line. Eventually one finds at the end 

 of a line, instead of a number, the name of a family of plants, to 

 which this particular plant belongs, and then turns over to the page 

 where this family is treated. Under each family is a similar key, to 

 be followed in exactly the same way, until finally one finds instead of 

 a number the common name and the scientific name of the plant in 

 hand. The process of identification is now completed, and the student 

 has found the name of the plant. 



In some cases, a reference is made in the key to a particular por- 

 tion of the family key. One then turns directly to this particular num- 

 ber in the family key, and continues his identification in the usual way. 



As a definite example of the use of the key, suppose that one has 

 in hand a branch of the White Oak, and that he does not know its 

 name. To determine its name, he will trace it through the following 

 steps in the key. Under the Key to the Groups, it agrees with line 

 la, which refers to Group 1, Woody Plants. Under this group it agrees 

 in structure with line la, which refers to 2; with line 2b, referring 



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